Main effects and interaction effect

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Main effects and interaction effect

Postby Sylvie23 » Wed Jun 13, 2012 10:51 am

Hi Everybody,

I did a factorial ANOVA analysis to find out if the score on 6 individual scales had a significant effect on the score of a dependent variable. In addition, I looked for interaction effects of the scores on these 6 scales on the depentent variable. My questions is:
What if there is NO main effect of a scale, but there is an interaction effect of two scales on the score of the dependents variable.
How can it be that if two scales both do not have a main effect, they do have an interaction effect? And what does this tell?

Is it like this? :
If someone only scores high on scale 1, this does'nt effect the dependent variable.
If someone only scores high on scale 2, this does'nt effect the depentent variable.
If someone scores high on BOTH scale 1 and scale 2 this has an effect on the dependent variable.

Can somebody help me out? Thank you!
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Re: Main effects and interaction effect

Postby statman » Wed Jun 13, 2012 1:07 pm

Simply not clear - How can there not be main effects (for example)?

Need more info. Also, see the Note below
See the note below

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